According to Cokayne, a French chronicle offers the only support for the modern assertion that Edward was styled 'of Norwich', and both Cokayne and Horrox suggest that the phrase 'de Norwik' found therein is a corruption or misreading of 'Deverwik', the usual French rendering for the phrase 'of York' at the time.[3]

Edward was knighted at the coronation of his cousin, Richard II, on 16 July 1377, and in May 1387 was admitted to the Order of the Garter. He was close to the King throughout his life, and benefited even in his youth from numerous royal grants and appointments. On 25 February 1390 the King created him Earl of Rutland, and on 22 March 1391 made him admiral of the northern fleet, and sole admiral the following November. In 1392 he became a member of King Richard's council, and was with the King during a campaign in Ireland in 1394-5, prior to which, although no patent has been found, he was created Earl of Cork. He used the styles of Rutland and Cork throughout the remainder of his life.[4]

On 11 July 1397 Richard II arrested his uncle, Thomas of Woodstock, 1st Duke of Gloucester. Rutland was granted Gloucester's office of Constable of England on 12 July, and was one of an eight-member commission which on 5 August determined to accuse Gloucester, the Earl of Warwick, and the Earl of Arundel of high treason. Rutland was later accused of having sent his servants to assist in Gloucester's subsequent murder at Calais, an allegation he denied. However on 28 September 1397 he received a large grant of Gloucester, Warwick and Arundel's forfeited lands, and on 29 September was created Duke of Aumale, a title which had earlier been granted to Gloucester on 3 September 1385.

On 16 September 1398 Aumale presided as constable over the aborted judicial combat between Henry Bolingbroke, the future Henry IV and Thomas Mowbray, 1st Duke of Norfolk, which ended with Bolingbroke and Norfolk being sent by King Richard into exile.[6]

In May 1399 Aumale accompanied King Richard to Ireland, and in the King's absence, Bolingbroke landed, towards the end of June, near Ravenspur, Yorkshire, with a small band of exiles. During the following three weeks Bolingbroke's forces were augmented by loyal Lancastrian supporters and were soon joined by the most powerful of the northern magnates, the Earls of Northumberland and Westmorland. King Richard's fatal decision to divide his army while still in Ireland has been attributed to advice from Aumale. The King sent some of his troops on ahead to North Wales under the command of the Earl of Salisbury, and about 19 July arrived at Milford Haven in South Wales with the rest of his forces. News of the strength of Bolingbroke's army then caused the King to desert the troops which were with him and travel to North Wales in an attempt to join Salisbury. However Salisbury's troops, having heard rumours of the King's death, had dispersed, and the army left behind by the King did so as well. Although he could have made his escape by sea, the King ensnared himself in negotiations with Bolingbroke. Meanwhile Aumale's father, Edmund of Langley, 1st Duke of York, who had been left in charge of the kingdom during King Richard's absence, and had raised an army on hearing of Bolingbroke's landing in Yorkshire, capitulated to Bolingbroke at Berkeley on 27 July. Aumale speedily deserted to Bolingbroke as well, and was reportedly wearing Bolingbroke's livery when he was among those sent by Bolingbroke to the King at Flint Castle.[8]

After his accession King Henry IV, in response to public animosity towards King Richard's closest associates, deprived Rutland on 31 August of his office of Constable of the Tower. On 20 October 1399 he was imprisoned at Windsor Castle, and on 3 November deprived of the dukedom of Aumale, but not his other titles. Rutland's period of disfavour was not long-lasting. The King confirmed him in his offices in connection with the Channel Islands and the Isle of Wight, and by 4 December 1399 had made him a member of his council.[9]

Rutland is alleged by a French chronicler to have betrayed to the King a conspiracy at the end of 1399 by a group of Richard II's former favourites who planned to murder Henry IV and his sons at a tournament at Windsor Castle on 6 January 1400. However according to Tait, contemporary English sources which describe the conspiracy make no mention of Rutland, and his role in it is open to doubt.[10]

In October 1400 the King made Rutland Keeper of North Wales, and on 5 July 1401[11] his lieutenant in Aquitaine. On 1 August 1402 Rutland's father died, and he succeeded to the Duchy of York,[12] at which time his earldom of Rutland became extinct by the terms of its charter, although he continued to sign himself Earl of Rutland. By May 1403 he was back in England. He was employed by the King in a campaign in Wales in the fall of that year, and on 12 November[13] was appointed Lieutenant for South Wales for three years. Both this and his appointment in Aquitaine proved very costly, and by June 1404 he had sold or pledged his plate and was contemplating mortgaging his lands to pay his troops in Wales.[14]

In February 1405 the Welsh rebel leader, Owain Glyndŵr, his son-in-law, Sir Edmund Mortimer, and Henry Percy, 1st Earl of Northumberland, entered into a tripartite indenture which proposed a threefold division of the kingdom,[15] an agreement apparently connected to a plot to free Mortimer's nephew from King Henry's custody and carry him into Wales. On 13 February 1405 the young Edmund Mortimer and his brother, Roger, were abducted from Windsor Castle, but quickly recaptured near Cheltenham. York's sister, Constance, was held responsible, and accused York of involvement in the failed abduction. He at first denied the charge, but later admitted to knowledge of the conspiracy. He was arrested, and imprisoned for 17 weeks at Pevensey Castle, after which he petitioned for release, and by October was gradually being returned to favour. His lands were restored to him on 8 December 1405, and in November 1406 he was again made Constable of the Tower and continued to serve in a military capacity in Wales.[16]

In the conflict over foreign policy between Henry IV and his heir, the Prince of Wales, which developed in the final years of Henry IV's reign, York apparently sided with the King. In 1412 he was again in France, in the company of the King's second son, Thomas, assisting the Armagnac party against the Burgundians.[17]

Memorial to Edward of Langley, 2nd Duke of York, erected by Queen Elizabeth I in Fotheringhay church

Henry IV died on 20 March 1413. York may have returned to England for a brief time after the King's death, but by June 1413 he was preparing to campaign in Aquitaine. In August he was in Paris, negotiating for a marriage between the new King, Henry V, and Catherine of Valois, but was back in England in October, and active in diplomatic negotiations in the final months prior to Henry V's invasion of France in 1415.[18]

A few days before the invasion of France, King Henry uncovered the Southampton Plot and the participation in it of York's younger brother, Richard of Conisburgh, Earl of Cambridge, for which the younger brother was beheaded on 5 August 1415. York himself was not implicated in the conspiracy, and he departed with the army for France. He was at the siege of Harfleur, where he made his will on 17 August 1415, then he commanded the van on the army's march through northern France. He commanded the right wing at the Battle of Agincourt on 25 October 1415, during which he became the highest-ranking English casualty. His death has been variously attributed to a head wound and to being 'smouldered to death' by 'much heat and pressing'. York was buried in the Church of St Mary and All Saints, Fotheringhay, where he had earlier established a college for a master and twelve chaplains. The monument now in the church was erected during the reign of Queen Elizabeth.[19]

Paradoxically, upon York's death the dukedom was inherited by his nephew, Richard Plantagenet, the son of the Southampton coup plotter who had been beheaded a mere two months earlier.

At the age of eight, York had been taken to Lisbon by his father and betrothed to Beatrice, the daughter of King Ferdinand I of Portugal, on 29 August 1381 as part of an alliance of England and Portugal against Castile, but after a rapprochement between Portugal and Castile the marriage was annulled by papal dispensation, and Beatrice married King John I of Castile.[20] Later, King Richard II suggested several possible brides for York, including Joan, sister of the King's wife, Isabella of Valois. Before 7 October 1398 York had married Philippa Mohun, third daughter of John Mohun, 2nd Lord Mohun (c.1320 – 15 September 1375), and Joan Burghersh (d. 4 October 1404), daughter of Bartholomew de Burghersh (c.1304 – 3 August 1355), 3rd Baron Burghersh, whose mother was Maud de Mortimer. Philippa brought little to her husband, her mother, Joan, having sold the Mohun estates in 1376. Moreover Philippa was apparently some 20 years older than York, and had had no issue by her two previous husbands, Walter Fitzwalter (d. 26 September 1386), 3rd Baron Fitzwalter, and Sir John Golafre (d. 18 November 1396). They had no issue. Philippa died on 17 July 1431 and was buried in Westminster Abbey.[21]

As a grandson of the sovereign in the male line Edward of Langley bore the arms of the kingdom, differenced by a label argent 3-point, per pale Castile and Leon.[23] In 1402 he inherited his father's arms, which were those of the kingdom differentiated by a label argent of three points, each bearing three torteaux gules.